Steve Smith's first Test century helped Australia reach 9 for 492 declared on a rain-affected day two of the fifth Ashes Test, with England's openers unbeaten at stumps on 0 for 32.

Smith, who began the day on 66, finished with 138 not out off 241 deliveries after rain prevented play from resuming until 2.30pm local time.

Australia's quicks had just over an hour at Alastair Cook (17 not out) and Joe Root (13 not out), but could not manage a breakthrough.

The English openers left the field when offered bad light just minutes before the scheduled end of play, but other than an lbw appeal on Cook from Peter Siddle (0 for 10) they were never really troubled.

It was a frustrating end to play for the Australians, who again had the run of play on day two.

Cook gave the ball to Jimmy Anderson (4 for 95) and Stuart Broad (1 for 128) after the covers came off in the hope they would be able to extract movement in the overcast conditions.

It wasn't long before Anderson claimed nightwatchman Siddle (23), who played across the line at a ball that took the top of off-stump.

Smith began tentatively but brought up his maiden Test century with a huge six, smashing a juicy Jonathan Trott medium-pacer over long-on.

It was just rewards for Smith, who came close to a ton at Old Trafford in the third Test.

"I was a little bit nervous. I was obviously pretty disappointed getting out for 89 at Old Trafford playing the shot I did," he said.

"I went down to Hads before that over with Trotty bowling - I thought I might be able to get a hold of one.

"I said 'What do you reckon about hitting one straight over his head?' and he said 'Just keep a clear mind' and the ball happened to be in the right spot and I got it out of the middle.

"I'm very happy to have got a hundred under the belt now. It has taken a little longer than I would have hoped but I feel like my game is in a good spot."

Haddin (30) was dismissed just a couple of balls after Smith brought up the milestone, cutting on to the wickets trying to dribble Trott down to third man.

Fireworks before declaration

Australia returned from the tea break trying to lift the run-rate with a declaration looming.

Debutant James Faulkner looked aggressive from the outset, and played a cameo innings of 23 from 21 deliveries before becoming the first Test scalp of Chris Woakes (1 for 96) when he holed out in the deep to Trott.

Starc (13) also looked to score quick runs before being bowled by Graeme Swann (2 for 95) trying to put him over cow corner.

All eyes turned to Clarke for the declaration as England brought play to a snail's pace.

The home side was at times booed by sections of the crowd who was frustrated by the slow over rate.

Ryan Harris provided what entertainment he could, taking to the English bowlers as he hit 33 from 27 deliveries, including two big sixes.

He was dismissed by an excellent Anderson caught-and-bowled after skying a ball trying to smash the England quick out of the ground.

Nathan Lyon was at the crease for just one delivery before Clarke decided to call time on the innings, giving his side just over an hour at the English batsmen.

No inroads for Australia

Australia's bowlers will have to improve on day three after not putting enough pressure on the English openers in the final session.

Haddin thought he had taken Root with a screamer down leg side off a wayward Starc delivery, but replays showed it had caught the Englishman's thigh guard.

Siddle (0 for 10) went up thinking he had Cook lbw, but umpire Aleem Dar was unmoved.

Replays showed the English skipper had got bat on the ball, which had also hit him outside the line of off-stump.

Faulkner (0 for 8) had an edge with his first ball in Test cricket, but Root was lucky as the ball fell short of first slip.